雙絞線用在什么場合?應注意什么
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來源：金環宇電線發(fa)布日期：2019-08-03 10:49
把兩(liang)根電(dian)(dian)(dian)(dian)(dian)(dian)線絞(jiao)合(he)在(zai)一(yi)起(qi)就可稱為(wei)雙(shuang)(shuang)(shuang)絞(jiao)線。事實上早在(zai)幾十年(nian)前就已使用雙(shuang)(shuang)(shuang)絞(jiao)線了，當(dang)時的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)子管收音機、還(huan)(huan)有(you)老(lao)的(de)(de)儀表工修理(li)過(guo)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)子電(dian)(dian)(dian)(dian)(dian)(dian)位差計、電(dian)(dian)(dian)(dian)(dian)(dian)子平(ping)衡電(dian)(dian)(dian)(dian)(dian)(dian)橋等，其電(dian)(dian)(dian)(dian)(dian)(dian)子管的(de)(de)燈絲電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(6.3V.AC);還(huan)(huan)有(you)用燈絲的(de)(de)指示燈;及一(yi)些交(jiao)流(liu)(liu)(liu)繼電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu);其供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)線用的(de)(de)就是(shi)雙(shuang)(shuang)(shuang)絞(jiao)線。原(yuan)因(yin)是(shi)這些電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)比信(xin)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)大得多，其頻率又是(shi)供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)頻率(50HZ)，因(yin)此極(ji)易產生(sheng)交(jiao)流(liu)(liu)(liu)噪聲的(de)(de)干擾(rao)。所(suo)以(yi)上述的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)除了要遠離信(xin)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)外，其供(gong)(gong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)線還(huan)(huan)用雙(shuang)(shuang)(shuang)絞(jiao)線以(yi)克服交(jiao)流(liu)(liu)(liu)噪聲的(de)(de)干擾(rao);對于(yu)脈沖電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)也常用雙(shuang)(shuang)(shuang)絞(jiao)線來傳輸信(xin)號(hao)。
雙絞線的應用
由于雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)柔軟、結構簡(jian)單、制造、安(an)裝、使用(yong)(yong)方(fang)便、串擾(rao)小，抗(kang)干(gan)擾(rao)能力強，因此得到了(le)(le)廣泛的應用(yong)(yong)。尤(you)其(qi)是(shi)在(zai)計(ji)算(suan)機的局域(yu)網(wang)(wang)中(zhong)，雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)充當了(le)(le)網(wang)(wang)絡(luo)信(xin)(xin)號(hao)(hao)的傳(chuan)輸(shu)工(gong)作，大(da)有(you)取代同軸(zhou)電(dian)纜的趨勢。近(jin)幾年雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)還(huan)在(zai)視(shi)(shi)頻(pin)(pin)信(xin)(xin)號(hao)(hao)的傳(chuan)輸(shu)中(zhong)被應用(yong)(yong)，如電(dian)視(shi)(shi)監控系統中(zhong)攝像頭的信(xin)(xin)號(hao)(hao)傳(chuan)輸(shu)就有(you)人采(cai)用(yong)(yong)雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)來傳(chuan)送，它就是(shi)利用(yong)(yong)了(le)(le)雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)抗(kang)電(dian)磁干(gan)擾(rao)的特點。在(zai)干(gan)擾(rao)復雜的環境(jing)中(zhong)傳(chuan)輸(shu)視(shi)(shi)頻(pin)(pin)信(xin)(xin)號(hao)(hao)具有(you)一(yi)(yi)(yi)定干(gan)擾(rao)抑制效果。雖然這種(zhong)傳(chuan)輸(shu)方(fang)式目(mu)(mu)前還(huan)有(you)爭(zheng)論，但(dan)仍有(you)不(bu)少(shao)廠(chang)家在(zai)探(tan)索推廣。雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)視(shi)(shi)頻(pin)(pin)傳(chuan)輸(shu)可分為無源(yuan)和(he)有(you)源(yuan)兩(liang)種(zhong)傳(chuan)輸(shu)方(fang)式，無源(yuan)方(fang)式只對信(xin)(xin)號(hao)(hao)進(jin)行(xing)了(le)(le)平衡-不(bu)平衡變換;有(you)源(yuan)方(fang)式對視(shi)(shi)頻(pin)(pin)進(jin)行(xing)了(le)(le)放(fang)大(da)和(he)頻(pin)(pin)率均衡處(chu)理，需要電(dian)源(yuan)，以上的傳(chuan)輸(shu)只需要用(yong)(yong)一(yi)(yi)(yi)對雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)。還(huan)有(you)一(yi)(yi)(yi)種(zhong)應用(yong)(yong)是(shi)采(cai)取5或6類(lei)雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)來傳(chuan)送VGA信(xin)(xin)號(hao)(hao)，即采(cai)用(yong)(yong)一(yi)(yi)(yi)套(tao)VGA雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)視(shi)(shi)頻(pin)(pin)發送、接(jie)收器(qi)，并采(cai)用(yong)(yong)單根5類(lei)非屏蔽(bi)雙(shuang)(shuang)絞(jiao)(jiao)(jiao)(jiao)線(xian)(xian)(xian)傳(chuan)輸(shu)VGA-RGBHV信(xin)(xin)號(hao)(hao)。其(qi)采(cai)用(yong)(yong)標準的568B接(jie)線(xian)(xian)(xian)方(fang)式，目(mu)(mu)前這樣(yang)的產(chan)品不(bu)少(shao)，但(dan)還(huan)要經過實踐(jian)的檢驗。
雙絞線的優點
◆抗干擾(rao)能力強
雙絞(jiao)線能有效地抑制(zhi)共模(mo)干擾，即使(shi)在強干擾環(huan)境下，雙絞(jiao)線也(ye)能傳送極(ji)好的(de)(de)(de)圖像信號。例(li)如樓(lou)宇的(de)(de)(de)電(dian)梯、設備房等處都(dou)會存在很強的(de)(de)(de)干擾，處于鬧市區的(de)(de)(de)建筑物也(ye)會受到來自周(zhou)圍(wei)環(huan)境的(de)(de)(de)各(ge)種干擾，雙絞(jiao)線的(de)(de)(de)強抗干擾能力比同軸電(dian)纜既有更大的(de)(de)(de)優勢。
◆可(ke)靠性高、使用方便
利用雙(shuang)絞(jiao)線(xian)傳輸視頻信(xin)號，在前端要接入專(zhuan)用發射機，在控制中心要接入專(zhuan)用接收機。這種雙(shuang)絞(jiao)線(xian)傳輸設備(bei)價格(ge)便宜，使用簡單，工(gong)作穩定。
◆總(zong)體造價降低
超5類非屏蔽電纜在目前的智能樓宇綜合布線(xian)中(zhong)被廣泛使(shi)用，其(qi)價(jia)格比同(tong)軸電纜要(yao)低，隨著超5類纜在通信(xin)中(zhong)的大量應用，價(jia)格還會進一(yi)步下(xia)降，因此(ci)使(shi)用雙絞線(xian)的經濟性和(he)便利性更為突出。
◆實時傳輸，即時監控(kong)
雙(shuang)絞線傳送的圖像(xiang)信(xin)號采用的是(shi)模擬(ni)信(xin)號技術，保證了監控系統的實時性(xing)，在控制室可以實時監控現場的圖像(xiang)。
使(shi)用雙絞(jiao)線(xian)應注意的(de)事項(xiang)
要(yao)使雙(shuang)絞(jiao)線(xian)發(fa)揮好(hao)作用(yong)，在(zai)(zai)(zai)使用(yong)中(zhong)還是(shi)很(hen)有講究的(de)，雙(shuang)絞(jiao)線(xian)是(shi)一種平衡傳輸(shu)線(xian)，因此應(ying)盡(jin)量采(cai)用(yong)平衡式傳輸(shu)線(xian)路(lu)，這樣(yang)可提高抗(kang)共(gong)模(mo)干擾(rao)(rao)的(de)能力。實驗(yan)證(zheng)明雙(shuang)絞(jiao)線(xian)通過接插(cha)件(jian)時(shi)，干擾(rao)(rao)信號會增大10%以(yi)上(shang)，干擾(rao)(rao)主要(yao)是(shi)由接插(cha)件(jian)的(de)耦合電(dian)容(rong)、漏電(dian)流等引(yin)起的(de)，因此最好(hao)少用(yong)接插(cha)件(jian)。雙(shuang)絞(jiao)線(xian)的(de)節(jie)距對(dui)抗(kang)干擾(rao)(rao)也(ye)有一定的(de)影響，從理論上(shang)講節(jie)距越(yue)小越(yue)好(hao)，但對(dui)用(yong)戶而言是(shi)無法改變的(de)，只(zhi)能在(zai)(zai)(zai)使用(yong)中(zhong)有所(suo)選擇和搭配，如(ru)采(cai)用(yong)不(bu)同節(jie)距的(de)雙(shuang)絞(jiao)線(xian)(網線(xian)就是(shi)這樣(yang)的(de))。盡(jin)管(guan)雙(shuang)絞(jiao)線(xian)有一定的(de)抗(kang)干擾(rao)(rao)能力，但在(zai)(zai)(zai)使用(yong)中(zhong)還應(ying)注意要(yao)與其它的(de)抗(kang)干擾(rao)(rao)手段相結合，如(ru)接地(di)-----最好(hao)單點接地(di)，并要(yao)考(kao)慮平衡對(dui)稱性問題;屏蔽(bi)-----要(yao)視(shi)具體情況(kuang)而定，如(ru)選用(yong)有屏蔽(bi)層的(de)雙(shuang)絞(jiao)線(xian)，但在(zai)(zai)(zai)屏蔽(bi)時(shi)不(bu)要(yao)引(yin)入地(di)環(huan)路(lu)，否則就沒(mei)有效果了,用(yong)屏蔽(bi)雙(shuang)絞(jiao)線(xian)時(shi)還應(ying)考(kao)慮分布(bu)電(dian)容(rong)的(de)影響。阻(zu)抗(kang)匹(pi)配-----對(dui)于(yu)長線(xian)傳輸(shu)時(shi)還應(ying)考(kao)慮阻(zu)抗(kang)匹(pi)配及帶負載問題。
